Superelastic NiTi Thin Layer Triggering High-Performance and High-Durability Thermoelectric Devices

The durability of thermoelectric devices (TEDs) has been a critical concern since they need to sustain frequent current or temperature shocks during operation. Herein, a shape memory alloy NiTi thin film is developed as a potential barrier layer to significantly enhance the durability of Bi 2 Te 3 -based TEDs. Atomic-resolution microscopy analysis confirms that the sputtered NiTi thin-film barrier layers coexist with B2 austenite and B19′ martensitic phases, which form NiTi/Bi 2 Te 3 joints exhibiting excellent superelasticity and strain recovery ability. Among these, the NiTi barrier layer at the equimolar ratio possesses the highest η e and η d (52.1% and 59.3%, respectively), exhibiting unique superelasticity. The NiTi/Bi 2 Te 3 jointed TEDs achieve a maximum cooling power density of 3.55 W·cm –2, much higher than other reported TEDs. Importantly, after 10,000 aging cycles of pulsed current, the decay of maximum cooling temperature difference for the NiTi/Bi 2 Te 3 jointed device is only half of that for the traditional Ni/Bi 2 Te 3 jointed one, exhibiting remarkably enhanced durability. This work reveals that the superelastic NiTi barrier layer as an outstanding stress buffer provides insight for realizing high-performance and high-durability TEDs.